U.S. patent number 5,037,424 [Application Number 07/609,644] was granted by the patent office on 1991-08-06 for instrument for orienting, inserting and impacting an acetabular cup prosthesis.
Invention is credited to Robert I. Aboczsky.
United States Patent |
5,037,424 |
Aboczsky |
August 6, 1991 |
Instrument for orienting, inserting and impacting an acetabular cup
prosthesis
Abstract
An instrument for implanting an acetabular cup prosthesis in a
patient's acetabulum. The cup is gripped on the base of the
instrument and is aligned and inserted in accordance with a plane
normal to the plane in which a patient is positioned and normal to
a line between the right and left anterior/superior iliac spines.
With the acetabular cup so aligned, the cup is impacted to be
retained in a prepared acetabulum. The instrument is actuated for
gripping the cup and is locked to maintain the cup gripped for the
aforenoted alignment, insertion and impaction, and is thereafter
unlocked and actuated for releasing the cup so that the instrument
can be removed from the cup without disturbing the position
thereof. The alignment of the cup is adjustable to accommodatae
various implantation situations as may occur.
Inventors: |
Aboczsky; Robert I. (Upper
Saddle River Rd., NJ) |
Family
ID: |
27037455 |
Appl.
No.: |
07/609,644 |
Filed: |
November 6, 1990 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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454432 |
Dec 21, 1989 |
4994064 |
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Current U.S.
Class: |
606/91 |
Current CPC
Class: |
A61F
2/4609 (20130101) |
Current International
Class: |
A61F
2/46 (20060101); A61F 005/04 () |
Field of
Search: |
;606/86,90,91,99,100
;623/18,22 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Hafer; Robert A.
Assistant Examiner: Rimell; Sam
Attorney, Agent or Firm: Cuoco; Anthony F.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of copending U.S.
application Ser. No. 454,432 filed by the present inventor on Dec.
21, 1989.
Claims
What is claimed is:
1. An instrument for orienting, inserting and impacting an
acetabular cup prosthesis, comprising:
first, second and third rods disposed in a common plane;
the first rod having a bottom with a shaped end and a slot in said
end;
the second rod extending angularly from the bottom of the first
rod;
the third rod displaceably coupled to the second rod and having an
end receivable in the slot in the end of the first rod and shaped
to match the shape thereof;
a spring captured between the second and third rods and normally
biasing the third rod so that the shaped end thereof is received in
the slot in the end of the first rod, whereby said first rod end is
adapted for supporting an acetabular cup;
means arranged with the second and third rods for displacing the
end of the third rod out of the slot to a position for gripping the
cup and for locking the end of the third rod in the displaced
position;
means arranged with the second rod for adjustably aligning the
gripped cup for insertion into a patient's acetabulum;
the second rod being disposed in a plane normal to the plane in
which the patient is supported and the adjustable aligning means
including a pair of bars, one of which bars, in accordance with the
side of the patient receiving the prosthesis, is disposed normal to
a line extending between the right and left anterior/superior iliac
spines of the patient, whereby the gripped cup is aligned for
insertion into the patient's acetabulum, and thereafter inserted
therein and impacted via impaction of the first rod to seat the
aligned and inserted cup; and
the displacing and locking means being unlocked and the third rod
displaced by the bias of the spring captured between the second and
third rods, whereby the end of the third rod enters the slot to
release the grip on the seated acetabular cup, whereupon the
instrument is removable from said cup without disturbing its
seating.
2. An instrument as described by claim 1, wherein the means
arranged with the second and third rods for displacing the end of
said third rod out of the slot to a position for gripping the cup
and for locking the end of the third rod in the displaced position
includes:
wedge means supported between the second and third rods below the
spring;
a spring for biasing the wedge means so that said wedge means is
normally ineffective for displacing the end of the third rod out of
the slot, and said wedge means being downwardly displaced against
the bias of the wedge means biasing spring for displacing the end
of said third rod against the bias of the spring captured between
the second and third rods out of the slot to the displaced
position; and
the wedge means being thereupon captured between the second and
third rods for locking the end of the third rod in said displaced
position.
3. An instrument as described by claim 2, wherein the locking means
being unlocked includes:
the third rod being displaced against the bias of the spring
captured between the second and third rods for displacing the end
of the third rod further out of the slot, whereupon the wedge means
is released from between the second and third rods; and
the third rod displaced by the bias of the spring captured between
the second and third rods, whereby the end of the third rod enters
the slot to release the grip on the seated acetabular cup.
4. An instrument as described by claim 1, wherein the means
arranged with the second rod for adjustably aligning the gripped
cup for insertion into a patient's acetabulum includes:
turret means supported by the second rod so as to be rotatable
about the axis thereof;
the pair of bars extending from the turret means in fixed angular
spaced relationship and rotatable with said turret means so that
the axis of each of the pair of bars is in a plane angularly
displaced from the common plane of the first, second and third
rods, with said angular displacement being adjustable commensurate
with the rotation of the turret means.
5. An instrument as described by claim 4, wherein:
the pair of bars extend from the turret means so as to be
displaceable upwardly and downwardly relative thereto to be out of
the way when not in use.
6. An instrument as described by claim 1, wherein:
the end of the first rod is shaped as a plurality of step-like
gradations and the end of the third rod received in the end of the
slot in the first rod is shaped in a plurality of matching
step-like gradations, whereupon said first rod end is shaped as a
plurality of continuous step-like gradations for being adapted to
support one of a plurality of acetabular cups on a corresponding
one of the continuous step-like gradations.
7. An instrument as described by claim 2, wherein:
the lowermost of the continuous step-like gradations is the
smallest in size for supporting a smallest cup and the uppermost of
said continuous gradations is the largest in size for supporting a
largest cup.
8. An instrument as described by claim 2, wherein: each of the
plurality of continuous step-like gradations is polygonal in shape
for engaging a polygonal shaped inner surface of the acetabular cup
for supporting said cup.
9. An instrument as described by claim 3, including:
a pin extending from within the bottom of the first rod and through
the lowermost of the step-like gradations at the end thereof;
the acetabular cups having at least one through hole into which the
pin extends when one of said cups is supported on a corresponding
one of the continuous step-like gradations; and
the pin having a shoulder for limiting the extension of the pin
into the cup hole.
10. An instrument as described by claim 5, wherein:
a spring is disposed within the bottom of the first rod and engages
the pin in spring biasing relationship so that the pin extends a
predetermined distance from the lowermost of the step-like
gradations at the end of the bottom of the first rod; and
said pin is displaced against the bias of the spring disposed
within the bottom of the first rod so that the uppermost of the
continuous step-like gradations supports the largest acetabular
cup.
11. An instrument as described by claim 1, including:
the end of the third rod being substantially parallel to the first
rod;
said third rod having a first section extending from the end
thereof at a first angle from the second rod; and
said third rod having a second section extending from the first
section at a second angle from the second rod, said second angle
being greater than the first angle.
12. An instrument as described by claim 7, wherein:
the spring captured between the second and third rods is captured
between the second rod and the first portion of the third rod near
the end thereof.
13. An instrument as described by claim 8, wherein:
the third rod is displaceably coupled to the second rod between the
spring captured between the second rod and the first portion of the
third rod and the end of the third rod below said spring.
14. An instrument as described by claim 8, wherein:
the third rod is displaced against the bias of the spring when the
second section of the third rod is displaced toward the second
rod.
15. An instrument as described by claim 4, wherein:
the polygonal shape of the continuous step-like gradations is
different than the polygonal shape of the inner surface of the
acetabular cup.
16. An instrument for orienting, inserting and impacting an
acetabular cup prosthesis, comprising:
first, second and third rods disposed in a common plane;
the first rod having a bottom with a shaped end and a slot in said
end;
the second rod extending angularly from the bottom of the first
rod;
the third rod displaceably coupled to the second rod and having an
end receivable in the slot in the end of the first rod and shaped
to match the shape thereof;
a spring captured between the second and third rods and normally
biasing the third rod so that the shaped end thereof is received in
the slot in the end of the first rod, whereby said first rod end is
adapted for supporting an acetabular cup;
means arranged with the second and third rods for displacing the
end of the third rod out of the slot to a position for gripping the
cup and for locking the end of the third rod in the displaced
position;
a pair of holes extending through the second rod in longitudinal
spaced relation, with the axis of one of said holes being in a
plane angularly displaced in one direction from the common plane of
the first, second and third rods and the axis of the other of said
holes being in a plane angularly displaced in another direction
from said common plane;
a bar extending through one of said holes in accordance with the
side of a patient which is receiving the prosthesis;
the second rod being disposed in a plane normal to the plane in
which the patient is supported and the bar being disposed normal to
a line extending between the right and left anterior/superior iliac
spines of the patient, whereby the gripped cup is aligned for
insertion into the patient's acetabulum, and thereafter inserted
therein and impacted via impaction of the first rod to seat the
aligned and inserted cup; and
the displacing and locking means being unlocked and the third rod
displaced by the bias of the spring captured between the second and
third rods, whereby the end of the third rod enters the slot to
release the grip on the acetabular cup, whereupon the instrument is
removable from said cup without disturbing its seating.
17. An instrument as described by claim 16, wherein the means
arranged with the second and third rods for displacing the end of
said third rod out of the slot to a position for gripping the cup
and for locking the end of the third rod in the displaced position
includes:
wedge means supported between the second and third rods below the
spring;
a spring for biasing the wedge means so that said wedge means is
normally ineffective for displacing the end of the third rod out of
the slot, and said wedge means being downwardly displaced against
the bias of the wedge means biasing spring for displacing the end
of said third rod against the bias of the spring captured between
the second and third rods out of the slot to the displaced
position; and
the wedge means being thereupon captured between the second and
third rods for locking the end of the third rod in said displaced
position.
18. An instrument as described by claim 17, wherein the locking
means being unlocked includes:
the third rod being displaced against the bias of the spring
captured between the second and third rods for displacing the end
of the third rod further out of the slot, whereupon the wedge means
is released from between the second and third rods; and
the third rod displaced by the bias of the spring captured between
the second and third rods, whereby the end of the third rod enters
the slot to release the grip on the seated acetabular cup.
Description
BACKGROUND OF THE INVENTION
A total hip replacement procedure has been developed by Howmedica
Division of Pfizer Hospital Products, Inc., Rutherford, N.J. and is
described in a monograph entitled The P.C.A. Primary Hip System
Surgical Technique prepared and published by Pfizer Hospital
Products, Inc. in 1988. Howmedica and P.C.A. are registered
trademarks of Pfizer Hospital Products, Inc.
The described surgical technique includes implanting an acetabular
outer shell or cup prosthesis after appropriately preparing the
acetabulum for the implantation. The actual implantation includes
orienting, inserting and impacting the acetabular cup in the
acetabulum.
Prior to the present invention, a variety of separate instruments
have been required to accomplish the implantation. This has been
found to be disadvantageous, particularly in view of the time and
inconvenience required in switching from one instrument to another,
which prolongs the overall operative time. In this connection it
will be noted that a major problem encountered in performing
surgical procedures such as herein referred to is the risk of
infection of the operative area. This risk increases as the
operative time increases, and hence it is most desirable to shorten
the operative time to the greatest extent possible. Moreover, due
to the nature of the procedure, it is imperative that it be
performed under circumstances most auspicious to the patient and to
the surgeon.
The invention disclosed in the aforementioned copending U.S.
application Ser. No. 454,432 overcomes the aforenoted disadvantages
and simplifies the implantation, in that only one instrument is
required for all of the segments of the procedure. With the
instrument therein described, an estimated fifteen to twenty
minutes of operative time is saved, which is desirable for the
reasons aforenoted.
The invention herein disclosed is an improvement over that
disclosed in the referenced co-pending U.S. Application in that a
locking arrangement is provided for the several operative members
of the instrument thereby facilitating the use thereof, and a more
versatile acetabular cup alignment arrangement is provided to
accommodate a variety of implantation situations as may from time
to time occur.
Accordingly, it is the object of the present invention to provide a
single instrument for orienting, inserting and impacting an
acetabular cup in a prepared acetabulum as part of a total hip
replacement procedure, wherein the use of the instrument is
facilitated and the instrument accommodates a wider variety of
implantation situations than has heretofore been the case.
SUMMARY OF THE INVENTION
This invention contemplates an instrument for orienting, inserting
and impacting an acetabular cup prosthesis for implanting said
prosthesis. The instrument includes an impact rod having a base
with a shaped end. A coupling rod is affixed to the base of the
impact rod and extends angularly therefrom. The coupling rod
supports a spring biased pivoting rod having a shaped end which is
pivotable away from and toward the shaped end of the impact rod.
The shaped end of the impact rod has a slot and the pivoting rod is
normally spring biased so that the end thereof is received in the
slot, whereby the shaped ends of the impact and pivoting rods
cooperatively mate for supporting the acetabular cup. When the
pivoting rod is pivoted away from the impact rod, the spring
compresses and the shaped end of the pivoting rod is displaced out
of the slot to grip the cup in a retaining relationship, whereupon
the cup is oriented and inserted in the acetabulum. A locking
device is arranged with the coupling and pivoting rods, whereby the
pivoting rod is maintained out of the slot to grip the cup without
the need for squeezing said rods as would otherwise be the case.
The coupling rod carries a rotatably displaceable alignment
arrangement which is used to adjustably align the acetabular cup to
accommodate a variety of implantation situations.
In using the instrument, the coupling rod is disposed normal to the
plane in which a patient is supported. The alignment arrangement
includes a bar which is rotatably adjustable about the axis of the
coupling rod and which is aligned normal to a line which crosses
from the patient's posterior superior iliac spine to the anterior
superior iliac spine, whereby the cup, gripped as aforenoted by the
locked instrument, is oriented for insertion into the
acetabulum.
Upon the cup being so oriented and inserted, the impact rod is
impacted, whereby the cup is seated in the acetabulum either by way
of a press fit or by cementing. Upon the cup being seated, the
instrument is unlocked and the pivoting rod is pivoted against the
bias of the spring, whereby the shaped end of the pivoting rod is
disposed in the slot in the shaped end of the impact rod for
releasing the instrument from the cup. The instrument is thereupon
removed from the cup without disturbing its seating.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded perspective representation showing the
instrument of the invention and an acetabular cup which is retained
thereby for being oriented, inserted and impacted into the
acetabulum of a patient, and further showing locking and alignment
arrangements according to the invention.
FIG. 2 is a fragmentary partially cut away perspective
representation showing a particular feature of the invention
wherein the base and end of the impact rod are adapted via a
biasing spring arrangement for receiving acetabular cups, and
further showing the locking arrangement of the invention.
FIG. 3 is a diagrammatic representation showing a line between the
right and left anterior/superior iliac spines, and which line is
used for aligning the instrument of the invention via the alignment
arrangement shown in FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
With reference to FIGS. 1 and 2, an impact rod is designated by the
numeral 2. Impact rod 2 has a base 4 integral therewith and base 4
has an end 6 integral therewith and shaped in a plurality of
step-like gradations 28 for supporting an acetabular cup 8 in a
manner which will be hereinafter described.
A coupling rod 10 is affixed to base 4 of impact rod 2 as by
welding or the like at 5 and extends angularly therefrom. A
clevis-like member 12 is formed integral with a pivoting rod 14.
Pivoting rod 14 extends first at a relatively small angle from
coupling rod 10 and then at a larger angle to form a handle or
gripping portion 14A of rod 14. Coupling rod 10 is supported in the
open portion of clevis-like member 12 and is secured therein via a
pin 16.
A spring 18 is disposed so as to be captured between coupling rod
10 and pivoting rod 14 above clevis 12. Pivoting rod 14 is normally
biased by spring 18 so that a shaped end 20 thereof extends
substantially parallel to impact rod 2 and is disposed in a slot 22
in shaped end 6 of impact rod 2. When rod 14 is pivoted about pin
16 toward rod 2 as by squeezing rod 10 and rod 14 at handle portion
14A, spring 18 is compressed and end 20 of rod 14 is displaced from
slot 22 as shown in FIG. 2. Thus, when end 20 of pivoting rod 14 is
disposed in slot 22, end 6 is adapted for supporting acetabular cup
8 on an appropriate continuous step-like gradation. When end 20 is
displaced out of the slot the cup is gripped by end 20 for
retaining the cup so supported.
With the arrangement just described rods 10 and 14 must be
continuously squeezed to maintain cup 8 gripped. This can be
cumbersome for the user since one of the user's hands is
continuously occupied for that purpose. The locking arrangement to
be next discussed overcomes this disadvantage.
Thus, clevis-like member 12 carries a spring biased locking device
designated generally by the numeral 13 and including a rod shaped
wedge member 15 having a curved end 15A and a handle 17, and a
biasing spring 19 surrounding the upper portion of wedge member 15.
Spring 19 is captured between handle 17 and the upper surface 12A
of clevis 12.
When cup 8 is positioned as aforenoted, device 13 is actuated by
depressing handle 17 against spring 19, whereby wedge member 15 is
displaced downwardly in the relatively small angular space between
rods 10 and 14 just enough to displace end 20 away from slot 22 to
grip cup 8, and to maintain end 20 so displaced, whereupon wedge 15
is captured between rods 10 and 14.
Thus, the hand of the user otherwise required to squeeze rods 10
and 14 to maintain cup 8 gripped is no longer required for that
purpose. Indeed, cup 8 can be pre-gripped and locked so gripped as
by a nurse or surgical assistant or the like, whereupon both of the
user surgeon's hands are free to implant cup 8, as will be
hereinafter described.
When cup 8 has been satisfactorily implanted, rods 10 and 14 are
squeezed for further displacing end 20 away from slot 22, whereupon
wedge 15 is released from between rods 10 and 14 and is upwardly
displaced via the biasing action of spring 19. Rods 10 and 14 are
released and end 20 is disposed in slot 22 via the biasing action
of spring 18, whereupon the instrument is easily removed from
implanted cup 8.
It will be understood that rods 2, 10 and 14 are in the same plane.
With continued reference to FIG. 1, rod 10 carries a through hole
24 and another through hole 26, said holes being longitudinally
displaced from each other above spring 18. The axis of one of the
holes 24 and 26 is displaced by approximately thirty-five degrees
in one direction from the common plane of rods 2, 10 and 14 and the
axis of the other of the holes 24 and 26 is displaced approximately
thirty-five degrees in another direction from the common plane of
the rods. As described in the aforenoted co-pending U.S.
application Ser. No. 454,432, said description being incorporated
herein by reference, one of the holes 24 and 26, depending on
whether the procedure is being applied to the patient's right or
left side, carries a removable alignment bar (not otherwise shown
herein) which will be hereinafter described for purposes of
comparison with the alignment arrangement of the present
invention.
While the removable alignment bar arrangement suffices for most
implantation situations, a situation can exist, depending on, among
other things, the manner in which a particular patient must be
oriented for properly implementing the implantation procedure,
which requires an alignment flexibility not thereby available. The
flexibility is provided by an adjustable alignment arrangement
designated generally by the numeral 25 in FIGS. 1 and 3.
Thus, and with particular reference to FIG. 1, rod 10 includes a
reduced diameter portion 27 near the top thereof. A turret member
29 is disposed on reduced diameter portion 27 so as to rest on a
spring washer 31 seated at the bottom of the reduced diameter
portion. Spring washer 31 may be the commercially available
Belleville washer which is well known in the art.
Turret 29 supports a pair of alignment bars 33 and 35 which are
fixedly spaced apart at an angle of seventy-two degrees. Bars 33
and 35 are pivotally supported on turret 29 via pivot pin means or
the like 37 for being displaceable upwardly and downwardly
therefrom so as to be out of the way when not in use. For purposes
of illustration, bars 33 and 35 are shown in dotted lines as being
downwardly displaced for the reason aforenoted.
The arrangement is such that turret 29 resting on spring washer 31
is rotatably displaceable about the axis of rod 10 in clockwise and
counterclockwise directions as shown by the arrow for purposes of
aligning the instrument as will be hereinafter described.
With reference to FIGS. 1 and 2, it will be seen that end 6 of
impact rod 2 is formed in step-like gradations 28 as aforenoted,
with four such gradations being shown for purposes of illustration.
The smallest gradation is at the bottom of end 6 and the largest
gradation is at the top thereof. Each of the gradations 28 is
shaped in a polygonal configuration, with a hexagon being shown for
purposes of illustration.
Each of the step-like gradations 28 is adapted for supporting an
acetabular cup 8 of a different size, i.e. diameter and depth.
Thus, the smallest acetabular cup 8 fits on the lowermost gradation
28 and the largest acetabular cup fits on the uppermost gradation
28. In this regard, it will be recognized that acetabular cups 8
are substantially semi-spherical in shape and have an internal
polygonal mounting rim 30 extending circumferentially therearound.
For purposes of illustration, surface 30 is shown shaped as a
decagon.
Thus, as will be discerned from FIG. 1, an acetabular cup 8 of a
desired size is disposed over end 6, with the appropriate gradation
28 at least partly engaging internal rim 30 of cup 8. With the
polygonal configuration of gradations 28 and rim 30 being different
as described, the painstaking and time consuming alignment of each
of the gradation sides with each of the rim sides is avoided as
would not be the case if both polygonal configurations were the
same.
Cup 8 is fabricated with a through hole 32 on the bottom thereof as
will be recognized by those skilled in the art. While hole 32 is
shown as being centrally disposed, some implantations may require
the hole to be off center. Indeed, cup 8 may have several such
holes in various locations at the bottom thereof to provide a
desired flexibility in usage. A pin 34 extends from the lowermost
gradation 28 and into hole 32. Pin 34 has a shoulder 35 and is
spring biased via a spring arrangement 36 as shown in FIG. 2,
whereby the pin is displaceable into and out of end 6 and base 4 as
will be discerned from the Figure. The purpose of pin shoulder 35
is to limit the extension of pin 34 into hole 32 to prevent the pin
from extending through the hole into the acetabulum. The pin is
displaceable against the bias of spring arrangement 36 so that end
6 can receive the largest acetabular cup 8 on the uppermost
polygonal gradation 28.
With an acetabular cup 8 so disposed on end 6, cup 8 is gripped and
locked gripped as aforenoted.
USE OF THE INVENTION
In using the instrument described and with an acetabular cup 8
gripped and locked gripped as aforenoted, coupling rod 10 is
disposed perpendicular to the plane in which the patient is
supported, which is a substantially horizontal plane. In the
invention described in the aforenoted co-pending U.S. application
Ser. No. 454,432, the removable alignment bar heretofore referred
to extends through one of the holes 24, 26, as the case may be, and
is aligned so as to be normal to a line 36 between the right and
left anterior/superior iliac spines normal to the patient's pelvic
line 38, with lines 36 and 38 shown in FIG. 3. While this alignment
arrangement may suffice for many cases, it is restrictive in that
only one position of the alignment bar for each side of the patient
is available as will now be understood. The present invention
recognizes that situations could well occur where other alignment
bar positions are required for properly implementing an
implantation procedure. Alignment arrangement 25 provides this
flexibility. In this regard, it is noted that, as heretofore
described, turret 29 is rotatably displaceable via the arrangement
including spring washer 31 so that the position of alignment bars
33 and 35 is adjustable relative to the common plane of rods 2, 10
and 14.
With continued reference to FIG. 3, turret 29 (FIG. 1) is rotated
to a desired alignment position as aforenoted. One of the alignment
bars 33 or 35 (FIG. 1), depending on whether the procedure is being
applied to the patient's right or left side and shown as bar 33 for
purposes of illustration, is aligned so as to be normal to line
36.
The flexibility afforded by the alignment arrangement disclosed
herein will be readily discernable. The angular distance between
the two alignment bars 33 and 35 is fixed and the positioning of a
single alignment bar in one or the other of a pair of holes in bar
10 as has been otherwise been the case is eliminated. Further, the
position of the particular alignment bar relative to the common
plane of rods 2, 10 and 14 which has otherwise been fixed is now
adjustable, as is advantageous in accommodating a variety of
implantation situations.
With the instrument thus aligned, which accomplishes the proper
orientation of acetabular cup 8, the cup is inserted in the
previously prepared acetabulum and impact rod 2 is impacted,
whereby the cup is seated in the acetabulum. Upon the cup being so
seated, locking device 13 is actuated for releasing the grip on the
cup, whereby the instrument is removed from the cup without
disturbing its seating, as aforenoted.
It will be understood by those skilled in the art that the
instrument herein described has a versatility in use in that it may
be used for an acetabular cup prosthesis which is either press
fitted or cemented into the acetabulum. Significantly, the
instrument saves a considerable amount of operative time since it
incorporates several different instruments and eliminates the time
required in switching from one instrument to the other.
The instrument can be fabricated from stainless steel, chrome
steel, cobalt steel or titanium so as to have a height and length
and an overall weight acceptable for orthopaedic surgeons, and for
meeting the demands of working within a relatively small cavity and
having enough maneuvering space as is required.
The design of the instrument is such that it retains the acetabular
cup in an ideal position, and holds it firmly so that even within
the bony acetabulum, the cup may be maneuvered to obtain ideal
alignment. The tool itself has the ability to withstand high
temperatures necessary for sterilization processes prior to use.
Further, its simplified design renders it easy to learn its usage
and to receive wide acceptability by the orthopaedic community. The
particular arrangements disclosed for locking the instrument in an
acetabular cup gripping mode and for providing adjustable alignment
of the cup enhance said usage.
It will be understood that the instrument may be fabricated for
accommodating both alignment arrangements herein described, i.e.
holes 24 and 25, and turret and angularly spaced bars 35 and 37,
whereby the user may select an alignment arrangement most suitable
for a particular situation.
Although the invention has been described with reference to an
acetabular cup having an internal rim with a particular polygonal
configuration such as illustrated in the aforementioned "Howmedica"
system, it will be understood that the instrument may be modified
to be adaptable to any such system wherein the cup has an internal
rim configuration which is circular, square, triangular, or any
other shape, the same being within the scope of the invention.
Thus, the instrument may be modified for use with the "Richards"
system, the "Zimmer" system, the "Protek" system, the "De Puy"
system, and all other systems using a press fit or cemented
acetabular component.
With the above description of the invention in mind, reference is
made to the claims appended hereto for a definition of the scope of
the invention.
* * * * *